AlcB

Siderophore biosynthesis protein domain

SMART accession number:

SM01006

Description:

AlcB is the conserved 45 residue region of one of the proteins of a complex which mediates alcaligin biosynthesis in Bordetella and aerobactin biosynthesis in E. coli and other bacteria. The protein appears to catalyse N-acylation of the hydroxylamine group in N-hydroxyputrescine with succinyl CoA - an activated mono-thioester derivative of succinic acid that is an intermediate in the Krebs cycle.

This entry represents a conserved 45 residue region found in one of the proteins from a siderophore biosynthesis complex [(PUBMED:9266668)]. The siderophore produced by this complex varies with species, e.g. alcaligin is produced in Bordetella, aerobactin in Escherichia coli and mycobactin in mycobacteria. The protein appears to catalyse N-acylation of the hydroxylamine group in N-hydroxyputrescine with succinyl CoA - an activated mono-thioester derivative of succinic acid that is an intermediate in the Krebs cycle [(PUBMED:15719346)].

We previously cloned a B. bronchiseptica (Bb) genomic DNA fragment thatcomplements a Bb alcaligin biosynthesis mutant, and reported theidentification of a gene, alcA, with predicted protein sequence similarityto siderophore biosynthesis enzymes from other organisms. In the presentstudy we show that further nt sequencing of this region revealed two openreading frames (ORFs) 3' to alcA that encode putative proteins AlcB andAlcC, with significant sequence similarity to the aerobactin biosynthesisenzymes IucB and IucC, respectively. RT-PCR analysis indicated that thethree ORFs are encoded on a single transcript, and that this operon isrepressed at the transcriptional level by Fe. Primer extension analysisplaced the transcriptional start point (tsp) 35 nt from the 5' end of theFur consensus sequence and 188 nt from the putative start of translationof AlcA.